It has long been a problem in commercial kitchens to remove the smoke, grease and odors generated above the cooking units. This problem has been addressed in both duct and ductless hoods positioned above the cooking ranges, grills and deep fat fryers. In a ductless system, the cooking discharges are passed through a filter and the filtered air returned to the kitchen. Although such systems may pass a sufficient volume of air for effective filtration, they must be designed within critical dimensions.
Therefore, ducted systems are often preferred for exhausting cooking discharges through a series of filters and out into the atmosphere.
Prior art exhaust systems for such systems generally include exhaust hoods located over a cooking area, a series of grease removal filters mounted in these hoods and a hood exhaust fan, usually located on the roof. The filters in the hoods are highly inefficient since they are designed to remove only the largest grease particles from the cooking exhaust, and there is no means provided in these filters for removing smoke or odors from the exhausted air.
Hood exhaust fans generally employed in the known systems are of a centrifugal up-blast which move the air stream through the filters and discharge it vertically into the atmosphere. Such fans depend on wind currents to carry away the smoke, odors and grease laden air.
Local rules which concern regulation of restaurant exhaust vary from place to place, and it is generally illegal to discharge cooking effluents into the atmosphere which adversely affect the environment. Furthermore, many fire regulations are addressing the problem of grease build-up which develops on the roof around the hood exhaust fan.
It is therefore an object of this invention to substantially eliminate all of the particles from exhaust cooking air and to further eliminate the grease build-up associated with exhaust fans known in the prior art.
Additionally, many of the prior art systems are balanced when they are installed to assure that a proper amount of air is exhausted from the cooking area and that this air is matched with an appropriate amount of make-up air to guarantee the elimination of a smoke build-up around the cooking areas. In general, this make-up air consists of either air conditioning or heating, depending on the season, regulated in the commercial establishment.
As the prior art systems are operated, grease builds up on filters, exhaust ducts and exhaust fan blades, reducing the amount of air that can be exhausted from the cooking area. Although these filters and exhaust ducts can be cleaned, generally cleaning does not keep up with the grease build-up and nothing is done regarding the build-up of grease on the exhaust fan blades. An improper air balance eventually results in these systems, and the proportion of make-up air to exhaust air is unbalanced. When more air is exhausted than the amount of make-up air in the area, a vacuum is created, conversely when less exhaust than make-up air is present, entrances to the area (e.g., doors and windows) bulge. A drain on the energy systems of the establishment thus occurs and the system becomes unbalanced, inefficient and costly.
It is therefore another object of the inventive system to substantially filter all of the smoke and grease from the cooking exhaust prior to releasing it into the surrounding atmosphere.
It is further an object to control the flow quantity of the cooking exhaust through the inventive system to thus maintain a constant air flow and provide a balanced and more cost effective air filtration system.